The present invention relates in general to belt conveyors, and more particularly to idler rollers for conveyor belts.
Conveyor belts are widely used for transporting a variety of materials, e.g. sand, gravel, from one location to another. Such conveyor belts include not only flat bed conveyor belts, but also conveyor belts having a troughed configuration for improved retention of transported material. Conveyor belts typically run on a system of idler rollers with rotational power provided by a prime mover. Since the idler rollers associated with such conveyor belts experience considerable use, attention has been given to improving their reliability.
Idler rollers used with conveyor belts are typically exposed not only to continuous friction due to motion of the conveyor belt, but also to a wide variety of foreign matter. The foreign matter frequently presents serious wear problems to the moving surfaces associated with the idler rollers. Such foreign matter originates from a wide variety of sources and frequently originates from materials carried by the conveyor belt, e.g., sand, gravel, et cetera. Such materials have the potential of not only reducing the effect of lubricants employed to neutralize friction in idler roller assemblies, but also may cut and abrade associated bearing surfaces. As a result of such abrasive action, idler rollers are frequently replaced.
In addition to the foregoing, uneven distribution of load material on the conveyor belt may result in relative movement of an idler roller. Such relative movement not only acts to introduce additional wear on load bearing surfaces, but also causes axial displacement of the idler roller relative to the support shaft about which rotation occurs. This frequently not only disturbs the operation of the conveyor belt, but further impacts other related processes which rely on an uninterrupted operation of the conveyor belt.
Additionally, idler rollers used with conveyor belts are continuously exposed to friction resulting in a heat build-up. Heat build-up within the idler rollers presents serious heat wear problems to the idler rollers. Heat build-up not only reduces the effect of lubricants employed to neutralize friction in idler roller assemblies, but also may cause excessive wear and tear on the idler rollers. As a result of heat wear problems, idler rollers are frequently replaced.
The U.S. Pat. No. 666,164 to Titus, issued on Jan. 15, 1901, for Roller Mechanism For Conveyor Belts, discloses a pair of inclined laterally-extended tubular rollers, held in position at a lower end by a circumferential rib and an associated collar, and at an upper end by a shoulder and associated shoulder cap. Lubrication may be introduced into the assembly through an associated funnel arrangement. The rollers are supported by a tubular shaft. At the distal end of the tubular shaft is the lubricant inlet opening.
The U.S. Pat. No. 858,612 to Mason, issued on July 2, 1907, for Rollers For Belt Conveyors, discloses the use of lateral-extended tubular rollers, inclined or projected in a direction transverse to the direction of travel of the conveyor belt to form a trough roller assembly.
The U.S. Pat. No. 3,648,824 to Speck, issued on March 14, 1972, for Idler Roller Device For Troughed Conveyor Belts, discloses an arrangement for the reduction of friction through the use of a smooth bearing surface of a metal construction engaging a urethane, surface. The patent to Speck further discloses an axial thrust bearing, e.g., a spherical ball bearing, disposed between an upper end of a roller and a support shaft. A pair of idler rollers are mounted on an upwardly and rearwardly inclined support shaft to exert a downward thrust to maintain the rollers on the support shaft.
The U.S. Pat. No. 4,266,662 to Reid, issued on May 12, 1981, for Trough Roller Assembly, discloses a radially projecting shoulder at the distal end of a support shaft, and an interfitting groove to prevent axial movement of the idler roller with respect to the support shaft.
In the U.S. Pat. No. 1,371,290, to Armstrong granted on Mar. 15, 1921, for Belt Supporting Pulley System, there is disclosed an idler pulley for supporting a conveyor belt. The pulley has a tubular shaft. A lubricant is fed into the tubular shaft. Radial openings in the tubular shaft enable the discharge of the lubricant to the bearing surface of the pulley.
In the U.S. Pat. No. 1,255,658, to Stephens issued on Feb. 5, 1918, for Carrier For Belt Conveyers, there is disclosed a belt conveyor having a roller. The roller is supported by a hollow shaft through a hub. Grease is fed into the distal end of the tubular shaft. Radial openings are provided in the tubular shaft to enable grease to be applied to the bearing surface of the hub.
The British publication by Schmidt, No. 1,454,875, published on Nov. 3, 1976, by the British Patent Office, entitled Improvements In Or Relating To Furnace Conveyor Rolls, there is disclosed a cooled furnace conveyor roll having a hollow roll body and a stub axle. A gaseous coolant is introduced through the stub axle into the cavity between the roll body and the internal body, and is exhausted through the internal body via holes in the casing of the internal body. Cooling is affected by pumping air as a coolant through the cavity between the roll body and the internal body. The air is extracted through the internal body via passages in the casing of the inner body. The air is employed for cooling the roll body.
Heretofore external keeper seals were employed in conjunction with idler rollers disposed for supporting conveyor belts having a troughed configuration. The purpose of the external keeper seals was to inhibit the penetration of moisture and dirt in the area between the shaft and the axial opening of the idler roller. Idler rollers were heretofore employed for supporting conveyor belts which comprised a solid shaft having openings for reducing the build-up of heat. It was found that such an arrangement was not effective for reducing heat build-up in idler rollers, but rather the idler rollers were heating excessively on faster speed belts. As a consequence thereof, the idler rollers were becoming worn rather quickly.